“NASA's Pathfinder, Pathfinder Plus, Centurion and Helios Prototype were an evolutionary series of solar- and fuel-cell-system-powered unmanned aerial vehicles. AeroVironment, Inc. developed the vehicles under NASA's Environmental Research Aircraft and Sensor Technology (ERAST) program. They were built to develop the technologies that would allow long-term, high-altitude aircraft to serve as “atmospheric satellites”, to perform atmospheric research tasks as well as serve as communications platforms”. – Wikipedia

Photo: The solar-electric Helios Prototype flying wing is flies over the Hawaiian islands of Niihau and Lehua during the first solar-powered test flight July 14, 2001 from the U.S. Navy's Pacific Missile Range Facility on Kauai, HI. The 18-hour flight was a functional checkout of the aircraft's systems and performance in preparation for an attempt to reach sustained flight at 100,000 feet altitude later in the summer. (Photo Courtesy of NASA/Getty Images)

Robert The Bruce's army from The Clanranald Trust during a rehearsal for the Battle of Bannockburn re-enactment performance which will be staged at the Bannockburn Live Event in Bannockburn, the 700th anniversary of the battle, on June 27, 2014. (Photo by Andrew Milligan/PA Wire)

Young girls attend a training session in MGFSO Olympic reserve school in Moscow on May 30, 2016. (Photo by Kirill Kudryavtsev/AFP Photo)

In this Wednesday, June 8, 2016 photo, Joe Giles, an actor portraying a zombie in “The Walking Dead”, poses with social media reporter Danielle Datu during a walker boot camp at Universal Studios Hollywood in Los Angeles. (Photo by Jae C. Hong/AP Photo)

A man walks though Times Square in high heels during unseasonably warm weather on Christmas Eve in the Manhattan borough of New York December 24, 2015. (Photo by Carlo Allegri/Reuters)

A Burmese monk feeds the seagulls at a Yangon river jetty February 8, 2012 in Yangon, Myanmar. (Photo by Paula Bronstein/Getty Images)

China has recently relaxed its one child policy that was used to control a burgeoning population. A couple has their wedding photo taken in an old quarter of Beijing on May 24, 2016. (Photo by Michael Robinson Chavez/The Washington Post)

Kaden Bringsplenty brings his horse to the starting line as Native Americans from all over the United States participate in an Indian relay race over Memorial Day weekend at the Osage County Fairgrounds in Pawhuska, Oklahoma, U.S. May 30, 2021. (Photo by Stephanie Keith/Reuters)